<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box{
            width: 400px;
            height: 400px;
            background-color: pink;
            /*盒子阴影：默认是外阴影*/
            /*格式：box-shadow: h-shadow v-shadow blur spread color inset(可选，默认外阴影)*/
            box-shadow: 0px 0px 10px 20px green inset;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>